1. Field of the Invention
The present invention relates to a coding apparatus which performs coding by switching between intra-frame coding and inter-frame coding, a coding method, and a coding system.
2. Description of the Related Art
Intra-frame coding in which intra-frame prediction is utilized and inter-frame coding in which inter-frame prediction is utilized are used as a technique of performing compression coding of moving image data. In the intra-frame coding, a difference between pixels adjacent to each other in a frame is obtained to perform coding, thereby compressing the moving image data. In the inter-frame coding, a high correlation between continuous frames is used to obtain a difference between preceding and subsequent frames of a coding object frame, and coding is performed to compress the moving image data. A high compression rate and image quality can be realized by switching between the two coding techniques according to the frame.
However, because the frame cannot be reproduced alone in the inter-frame coding, video images are hardly trimmed or combined in frame unit during editing. There is also generated a problem in special reproduction such as fast-forward and reverse reproduction in searching for an editing point. The image quality is deteriorated, when the inter-frame coding data is further transformed into an All-Intra-frame coding moving image in order to perform the editing in frame unit. When the editing is abandoned in frame unit to perform the editing in GOP (Group of Picture) unit, inter-frame coding data is hardly dealt with because a degree of freedom is lowered. When only the All-Intra-frame coding is used from the time of recording, a recording time in medium is shortened because of the low compression rate.
For example, Jpn. Pat. Appln. KOKAI Publication Nos. 2000-312362 and 8-265694 discloses associated techniques.